1. Field of the Invention
The present invention relates to an error correction apparatus and an optical disk player using the same.
2. Description of the Related Art
In a digital versatile disk (DVD) player and the like, an analog signal read from the DVD is converted to a digital signal and the digital signal is subjected to an 8-16 conversion when reproducing a DVD. A single error correcting codes (ECC) block worth of digital signal obtained by the 8-16 conversion is stored in a buffer memory, an error correction is performed by reading the signal, and the error corrected digital signal is decoded.
The error correction is performed on the digital signal read from the DVD in units of the ECC.
FIG. 1 is a view for explaining the format of the ECC block.
Data BM,N (0xe2x89xa6Mxe2x89xa6191, 0xe2x89xa6Nxe2x89xa6171) shown in FIG. 1 is information data composed of 16 sectors each having 172 bytes 12 rows.
Also, data BM,N (0xe2x89xa6Mxe2x89xa6207, 172xe2x89xa6Nxe2x89xa6181) is an inner code parity of a Read-Solomon code.
Namely, the inner code parity (172xe2x89xa6Nxe2x89xa6181) is an inner code parity of the information data BM,N (0xe2x89xa6Nxe2x89xa6171).
Also, the data BM,N (192xe2x89xa6Mxe2x89xa6207, 0xe2x89xa6Nxe2x89xa6171) is an outer code parity of the Read-Solomon code.
Namely, the outer code parity BM,N (192xe2x89xa6Mxe2x89xa6207) is an outer code parity of the information data BM,N (0xe2x89xa6Mxe2x89xa6192).
Below, execution timing of processing for storing the ECC block worth of digital signal in the buffer memory and the processing for the error correction will be explained.
FIG. 2 is a view for explaining an execution timing of processing for storing one ECC block worth of the digital signal and an error correction.
In FIG. 2, the abscissa axis indicates time and the ordinates axis indicates a data amount.
As shown in FIG. 2, the one ECC block worth of digital signal is written in the buffer memory between the time xe2x80x9c0xe2x80x9d and xe2x80x9ct1xe2x80x9d. Next, the one ECC block worth of digital signal written during the time between xe2x80x9c0xe2x80x9d and xe2x80x9ct1xe2x80x9d is read and the error correction is performed between the time xe2x80x9ct1xe2x80x9d and xe2x80x9ct2xe2x80x9d. Also, the next one ECC block worth of the digital signal is written in the buffer memory during the time xe2x80x9ct1xe2x80x9d and xe2x80x9ct2xe2x80x9d. Next, the one ECC block worth of digital signal written in the buffer memory between the time xe2x80x9ct1xe2x80x9d and xe2x80x9ct3xe2x80x9d is read and the error correction is performed between the time xe2x80x9ct3xe2x80x9d and xe2x80x9ct4xe2x80x9d.
In this way, in the DVD player of the related art, one ECC block worth of digital signal is first stored in the buffer memory, and the error correction is performed by reading the digital signal from the buffer memory. Therefore, at least the time for xe2x80x9ct2xe2x80x9d is required from the start of the writing to the buffer memory to the completion of the error correction.
Namely, the time from the start of writing the ECC block to the buffer memory to the completion of the error correction affects the access time or reproducing time of the DVD player.
Recently, there is a demand for a shorter accessing time or reproducing time of the DVD player, so it has been desired that the time from the start of writing the ECC block to the buffer memory to the completion of the error correction be shortened.
An object of the present invention is to provide an error correction apparatus and an optical disk reproducing apparatus which can shorten the access time of a DVD player by shortening the time from the start of writing the ECC block to a buffer memory to the completion of an error correction.
To attain the above object, the error correction apparatus of the present invention performs an error correction in units of an error correction code block composed of information data, an inner code parity indicating the error correction code for every row of the information data and an outer code parity indicating an error correction code for every column of the information data when a plurality of bit data forming the information data is arranged in matrix, and comprises: a memory means for storing the error correction code block included in a signal read from a memory medium by inputting the error correction code block as units of the row of the information data and the inner code parity corresponding to the row; and an error correction means for reading the row of the information data and the inner code parity corresponding to the row among the error correction code block stored in the memory means and performing an error correction of the read row of the information data by using the read inner code parity data at the timing before all of the data constituting the error correction code block has been stored in the memory means, in parallel with the operation of storing in the memory means the remaining data constituting the error correction code block.
In the error correction apparatus of the present invention, the error correction code block included in the reproducing signal read from the recording medium is successively stored in the memory means in units of a row including the corresponding inner code parity.
Then, in parallel with the storing processing, the row of the information data already stored in the memory means and the inner code parity corresponding to the row from among the error correction code block during being stored in the memory means are successively read, and an error correction of the read row is carried out by using the read inner code parity at the timing before all of the data constituting the error correction code block is stored in the memory means in the error correction means.
Preferably, in the error correction apparatus of the present invention, the error correction means terminates the operation of the error correction using the inner code parity on the error correction code block at the timing approximately matching to a timing when all of the data constituting the error correction code block data is stored in the memory means.
Preferably, in the error correction apparatus of the present invention, the error correction means starts the operation of the error correction at the timing after a first row of the information data and the inner code parity corresponding to the first row is stored in the memory means.
Preferably, in the optical disc reproduction apparatus of the present invention, the error correction means terminates the operation of the error correction using the inner code parity on the error correction code block at the timing approximately matching to a timing when all of the data constituting the error correction code block data is stored in the memory means.